<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <link rel="stylesheet" href="../重置样式表/reset.css">
  <title>Document</title>
  <style>
    #demo{
      width: 92vw;
      height: 40vw;
      margin: 0 auto;
      margin-top: 4vw;
      background-color: skyblue;
    }
  </style>
</head>
<body>
  <div id="demo"></div>
</body>
</html>